The relationship between two genes in Escherichia coli will be examined in order to contribute to an understanding in molecular terms of one of the mechanisms of evolution. The enzyme tryptophanase and the B protein of the enzyme tryptophan synthetase are closely related. It seems possible that the genes for these enzymes once evolved from a common ancestral gene which duplicated, diverged in function, and were separated genetically by translocation. This hypothesis predicts that residual homology may persist in these two genes. The research project will test for homology between the genes by genetic recombination and by DNA-DNA hybridization. The recombination experiments would use bacterial transduction systems, and would ask whether recombination between the genes for tryptophanase and tryptophan synthetase B protein takes place when homologous recombination is prevented by the use of appropriate deletion mutants. The hybridization experiments would assess the extent of hybrid formation between DNA's derived from the appropriate high frequency transducing phages and DNA's derived from the appropriate bacterial deletion mutants.